Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 12)

Quick Start Guide
Insert the battery ( ).
Upon purchase, charge the battery to start using ( ).
Insert the card ( ).
You can insert two cards.
Attach the lens ( ).
Align the red mount index on the lens with the red mount index on the
camera to attach the lens.
12
1.
2.
3.